1. Field of the Invention
This invention relates to valves for the draining of sumps, especially oil sumps on internal combustion engines.
2. Background and Prior Art
Motor oil breakdown over time and through hard use is an unavoidable problem. To effect an oil change, it has been necessary to remove a plug from the bottom of the oil sump and catch the oil in some container as it pours out. The person changing the oil is confronted with a dilemma: drop the plug at the point when oil is about to flow and let the plug fall into the oil catch container or accept the fact that some oil will pour over the fingers. There is some evidence that routine skin contact with used motor oil is not healthy and should be minimized.
The location of the drain plug must be at or near the bottom of the sump. Typically, it is located where the bottom of the sump meets the sides, at about a 45 degree angle. On farm machinery and many trucks, access to the drain plug is not a difficulty. The majority of automobiles and light trucks must be elevated to drain the oil.
On many vehicles, the drain plug is located at or near the lowest part of the vehicle and the almost universal use of a short bolt or plug reflects the need to limit exposure beneath the vehicle.
Numerous attempts have been made to resolve the problems which attend oil changes. U.S. Pat. No. 4,269,237 to Berger disclosed a check valve opened when a tube was inserted into a fitting screwed into the oil pan. The tube was attached by a bayonet fitting which extended away from the pan. A foam rubber sleeve was described which seems needed to minimize leakages.
U.S. Pat. No. 4,709,722 to Knapp describes a valve apparatus having a spring loaded check valve which is opened when a vacuum is drawn on the fitting. A external pump is required to open the valve.
U.S. Pat. No. 4,917,356 to Shirdavani discloses a poppet valve in a fitting screwed into the sump and which is activated by pulling a cable.
U.S. Pat. No. 4,940,209 to Fish discloses a ball type check valve inserted into an oil sump and activated by a lever affixed to a pipe which is screwed into the check valve fitting.
U.S. Pat. No. 5,048,578 to Dorf et al. is directed to a check valve and bayonet fitting for use with a pump to drain oil.
U.S. Pat. No. 5,630,451 to Bernard describes an insert for an oil sump which incorporates a plug valve.
U.S. Pat. No. 5,667,195 to McCormick discloses an oil drain valve similar in concept to a Schraeder valve.
None of the references described is simple and leak-proof. The number of patents indicates a long-felt need for a device of this type. The lack of such a device on the market indicates that the need has not been met.